Micro electro-mechanical system (MEMS) based hydraulic control system for full hybrid vehicles

ABSTRACT

A powertrain system in a hybrid vehicle includes a hydraulic device, a pilot valve, and a regulator valve. The pilot valve is operably connected to the hydraulic device and configured to actuate. The pilot valve includes at least one micro-electro-mechanical systems (MEMS) based device. The regulator valve is operably connected to the pilot valve and the hydraulic device. The regulator valve is configured to direct fluid to the hydraulic device based on the actuation of the pilot valve.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/393,388, filed Oct. 15, 2010, which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to a Micro Electro-Mechanical System (MEMS) basedhydraulic control system.

BACKGROUND

Passenger and commercial vehicles include various hydraulic devices.Valves allow fluid to flow from a pump to the hydraulic device. However,the valves may be large and expensive, adding weight and cost to thevehicle.

SUMMARY

A powertrain system in a hybrid vehicle includes a transmissionconfigured to selectively receive a torque from an engine and at leastone motor. The transmission includes a hydraulic device and a pilotvalve. The pilot valve is operably connected to the hydraulic device andconfigured to actuate. The pilot valve includes at least one MicroElectro-Mechanical System (MEMS) based device. A regulator valve isoperably connected to the pilot valve and the hydraulic device. Theregulator valve is configured to direct fluid to the hydraulic devicebased on the actuation of the pilot valve.

A vehicle includes an engine and at least one motor configured togenerate a torque. A transmission is configured to receive the torquegenerated by at least one of the engine and the at least one motor. Aclutch assembly is configured to transfer a torque from the engine tothe transmission. The transmission includes a hydraulic device operablyconnected to a pilot valve and a regulator valve. The pilot valveincludes at least one MEMS based device.

The powertrain system disclosed herein provides a reduced weight andcost solution to hydraulic control in a hybrid vehicle.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a Micro Electro-MechanicalSystem (MEMS) microvalve actuator.

FIG. 2 is a schematic cross-sectional view of a MEMS spool valve thatmay be used alone or in conjunction with the MEMS microvalve actuatorshown in FIG. 1.

FIG. 3 is a schematic diagram of powertrain system that may implementthe MEMS devices of FIGS. 1 and 2 in a hybrid vehicle.

FIG. 4 is a schematic box diagram of a first option for a pressurecontrol system for a hydraulic-controlled component within a powertrainfor a hybrid vehicle.

FIG. 5 is a schematic box diagram of a second option for a pressurecontrol system for the hydraulic-controlled component within apowertrain for a hybrid vehicle.

FIG. 6 is a schematic box diagram of a third option for a pressurecontrol system for a third hydraulic component within a powertrain for ahybrid vehicle.

FIG. 7 is a schematic box diagram of a fourth option for a pressurecontrol system for a fourth hydraulic component within a powertrain fora hybrid vehicle.

DETAILED DESCRIPTION

A powertrain system as described herein provides reduced weight and costsolution to hydraulic control in a hybrid vehicle. In one particularimplementation, the powertrain system may include a hydraulic device anda pilot valve. The pilot valve is operably connected to the hydraulicdevice and configured to actuate. The pilot valve includes at least oneMicro Electro-Mechanical System (MEMS) based device. A regulator valveis operably connected to the pilot valve and the hydraulic device. Theregulator valve is configured to direct fluid to the hydraulic devicebased on the actuation of the pilot valve. The use of a MEMS-baseddevice in the pilot valve reduces the weight and cost of the powertrainsystem.

FIG. 1 illustrates a Micro Electro-Mechanical System (MEMS) microvalve100 that provides a reduced weight and cost solution to hydrauliccontrol in a vehicle. The MEMS microvalve 100 may take many differentforms and include multiple and/or alternate components and facilities.While an example MEMS microvalve 100 is shown in the figures, thecomponents illustrated in the figures are not intended to be limiting.Indeed, additional or alternative components and/or implementations maybe used.

As discussed below, the MEMS microvalve 100 may be used to effecthydraulic control over one or more hydraulic components, especiallywithin a transmission. The MEMS microvalve 100 shown is only one type ofMEMS device that may be used as a control valve or control actuator forthe hydraulic components, and others, discussed herein.

While various MEMS devices are described in detail with respect toautomotive applications, MEMS devices may be used in other areas aswell. Further, terms such as “above,” “below,” “upward,” “downward,”etc. are used descriptively of the figures, and do not representlimitations on the scope of the invention, as defined by the appendedclaims.

Generally, MEMS devices may be considered as part of a class of systemsthat are physically small, having features with sizes in the micrometerrange. MEMS systems may have both electrical and mechanical components.MEMS devices are produced through micromachining processes. The term“micromachining” may generally refer to the production ofthree-dimensional structures and moving parts through processesincluding modified integrated circuit (computer chip) fabricationtechniques (such as chemical etching) and materials (such as siliconsemiconductor material). The term “microvalve” as used herein maygenerally refer to a valve having components with sizes in themicrometer range, and thus by definition is at least partially formed bymicromachining. As such, the term “microvalve device” may include adevice having one or more components with sizes in the micrometer range.MEMS devices may operate in conjunction with other MEMS (micromachined)devices or components or may be used with standard sized (larger)components, such as those produced by mechanical machining processes(e.g., a metal spool valve).

Referring to FIG. 1, the MEMS microvalve 100 includes a housing or body110. The MEMS microvalve 100 may be formed from several material layers,such as semi-conductor wafers. The body 110 may also be formed frommultiple layers. For example, and without limitation, thecross-sectioned portions shown may be taken through a middle layer ofthe MEMS microvalve 100, with two other layers existing behind and infront of (relative to the view in FIG. 1) the middle layer. The otherlayers of the body 110 may include solid covers, port plates, orelectrical control plates. However each of the layers is generallyconsidered part of the body 110, except where separately identified.

The MEMS microvalve 100 includes a beam 112 actuated by a valve actuator114. Selective control of the actuator 114 causes the beam 112 toselectively alter the flow of fluid between an inlet port 116 and anoutlet port 118. By varying the fluid flow between the inlet port 116and the outlet port 118, the MEMS microvalve 100 varies the pressure ina pilot port 120. As described herein, the pilot port 120 may beconnected to additional valves or devices in order to effect hydrauliccontrol thereof through a pilot signal which varies based upon thepressure in the pilot port 120.

The inlet port 116 is connected to a source of high-pressure fluid suchas a pump (not shown). The outlet port 118 is connected to alow-pressure reservoir or fluid return (not shown). For purposes of thedescription herein, the outlet port 118 may be considered to be atambient pressure, and acts as a ground or zero state in the MEMSmicrovalve 100.

The beam 112 moves in a continuously variable manner between a firstposition, illustrated in FIG. 1, a second position (not shown), andmyriad intermediate positions. In the first position, the beam 112 doesnot completely block the inlet port 116. However, in the secondposition, the beam 112 blocks the inlet port 116 to preventsubstantially all flow from the high-pressure fluid source.

A first chamber 122 is in fluid communication with both the inlet port116 and the outlet port 118. However, communication between the outletport 118 and the first chamber 122 (and also the inlet port 116) isrestricted by an outlet orifice 124. High volume or fast fluid flowthrough the outlet orifice 124 causes a pressure differential to buildbetween the first chamber 122 and the outlet port 118.

The beam 112 is pivotally mounted to a fixed portion of the body 110 bya flexure pivot 126. The opposite portion of the beam 112 from theflexure pivot 126 is a movable end 128, which moves up and down (asviewed in FIG. 1) to selectively, and variably, cover and uncover theinlet port 116.

When the beam 112 is in the second position, it allows little or no flowfrom the inlet port 116 to the first chamber 122. Any pressurized fluidin the first chamber 122 bleeds off through the outlet orifice 124 tothe outlet port 118. As the beam 112 of the MEMS microvalve 100 is movedtoward the first (open) position, the inlet port 116 is progressivelyuncovered, allowing faster flows of fluid from the inlet port 116 intothe first chamber 122. The fast-flowing fluid cannot all be drainedthrough the outlet orifice 124 and causes a pressure differential toform as the fluid flows through the outlet orifice 124, raising pressurein the first chamber 122.

As the inlet port 116 is further opened to the first position (as shownin FIG. 1), fluid gradually flows faster through the outlet orifice 124,causing a larger pressure differential and further raising the pressurein the first chamber 122. When the beam 112 is in the first position, itallows high flow from the inlet port 116 to the first chamber 122.Therefore, the pressure in the first chamber 122 can be controlled bycontrolling the rate of flow from the inlet port 116 through the firstchamber 122 and the outlet orifice 124 to the outlet port 118. Theposition of the beam 112 controls the rate of flow of the fluid from theinlet port 116, and thus the pressure in the first chamber 122.

The valve actuator 114 selectively positions the beam 112. The actuator114 includes an elongated spine 130 attached to the beam 112. Theactuator 114 further includes a plurality of first ribs 132 and aplurality of second ribs 134, which are generally located on opposingsides of the elongated spine 130. Each of the first ribs 134 has a firstend attached to a first side of the elongated spine 130 and a second endattached to the body 110. Similar to the first ribs 132, each of thesecond ribs 134 has a first end attached to the elongated spine 130 anda second end attached to the fixed portion of the body 110.

The elongated spine 130 and the first ribs 132 and the second ribs 134may appear illustrated in FIG. 1 as disconnected from the body 110.However, the elongated spine 130, the first ribs 132, and the secondribs 134 are formed from the same material and are connected to the body110 at some point in order to allow relative movement. However, theconnection may be below the cross-sectioned plane shown in FIG. 1.Generally, the elongated spine 130, the first ribs 132, and the secondribs 134 may be considered the moving portions of the actuator 114.

The first ribs 132 and the second ribs 134 are configured to thermallyexpand (elongate) and contract (shrink) in response to temperaturechanges within the first ribs 132 and the second ribs 134. Electricalcontacts (not shown) are adapted for connection to a source ofelectrical power to supply electrical current flowing through the firstribs 132 and the second ribs 134 to thermally expand the first ribs 132and the second ribs 134.

The actuator 114 is configured to be controlled by an engine controlunit (ECU) or other programmable device (not shown in FIG. 1) whichsupplies variable current to the first ribs 132 and the second ribs 134.As the first ribs 132 and the second ribs 134 expand due to sufficientcurrent flow, the elongated spine 130 moves or stretches downward (asviewed in FIG. 1), causing the beam 112 to rotate in the generallycounter-clockwise direction. The resulting movement of the beam 112causes the moveable end 128 to move upward (as viewed in FIG. 1) andprogressively block more of the inlet port 116.

Closing the inlet port 116 allows less (and eventually no) fluid to flowinto the first chamber 122, decreasing the pressure therein as the fluiddrains to the outlet port 118. Once the inlet port 116 is closed, theMEMS microvalve 100 is in the second position (not shown), and no pilotsignal is being communicated through the pilot port 120.

As the flow of current drops, the first ribs 132 and the second ribs 134contract and the elongated spine 130 moves upward (as viewed on the pagein FIG. 1), causing the beam 112 to rotate in the generally clockwisedirection. The resulting movement of the beam 112 causes the moveableend 128 to move downward (as viewed on the page in FIG. 1) andprogressively open more of the inlet port 116.

Opening the inlet port 116 allows more fluid to flow into the firstchamber 122, increasing the pressure therein as the fluid flow overcomesthe ability of the outlet port 118 to drain fluid from the first chamber122. Once the inlet port 116 is substantially open, the MEMS microvalve100 is in the first position (shown in FIG. 1), and a strong pilotsignal is being communicated through the pilot port 120.

In addition to the heat-actuated MEMS device shown in FIG. 1, othertypes of MEMS based actuators may be used in place of the MEMSmicrovalve 100 or in place of the actuator 114. In general, themicro-electro-mechanical system (MEMS) based device may include anydevice that has one or more electronic elements fabricated through anintegrated circuit technique (e.g., etching on a silicon wafer) and oneor more mechanical elements fabricated through a micromachining process(e.g., forming structures and moving parts with dimensions in themicrometer range). The electronic and mechanical elements may also beformed by other processes. In alternative or additional approaches orconfigurations, the MEMS-based device may include other elements withdimensions in the micrometer range, such as an electromagnetic fieldactuator, a piezoelectric actuator, a thermal actuator, an electrostaticactuator, a magnetic actuator, a shape memory alloy, a pressure sensor,a gyroscope, an optical switch, other MEMS-based devices, or anycombination thereof.

Referring now to FIG. 2, and with continued reference to FIG. 1, thereis shown a schematic cross-sectional view of a MEMS-based spool valve200. The MEMS-based spool valve 200 includes a housing or body 210. TheMEMS-based spool valve 200 may be formed from several material layers,such as semi-conductor wafers. The body 210 may also be formed frommultiple layers. For example, and without limitation, thecross-sectioned portions shown may be taken through a middle layer ofthe MEMS-based spool valve 200, with two other layers existing behindand in front of (relative to the view in FIG. 2) the middle layer.

The MEMS-based spool valve 200 includes a slider 212 configured to bemovable to the left and to the right (as viewed on the page in FIG. 2)within a cavity 214 defined by the body 210. The slider 212 is actuatedby fluid pressure on a piloted surface 216, which is in fluidcommunication with a piloted chamber 220 of the cavity 214. Selectivevariation of pressure within the piloted chamber 220 alters the forceapplied to the piloted surface 216. The piloted chamber 220 may be influid communication with a pilot signal, such as the pilot signalproduced by the pilot port 120 of the MEMS microvalve 100 shown in FIG.1.

The slider 212 is formed with an elongated plate having a pair ofoppositely disposed arms extending perpendicularly at a first end of thebody so that the slider 212 is generally a T-shape, having the pilotedsurface 216 at a wider longitudinal end of the slider 212, and a countersurface 222 at a relatively narrower opposing longitudinal end of theslider 212. The cavity 214 is also generally a T-shape.

The body 210 defines a number of ports connecting with the cavity 214,some of which may be formed in cross-sectioned layer and some of whichmay be formed in other layers. The ports include a supply port 224,which is adapted to be connected to a source of high pressure fluid,such as a transmission pump (not shown). The supply port 224 may beconnected to the same source of high-pressure fluid as the inlet port116 of the MEMS microvalve 100 shown in FIG. 1. The body 210 alsodefines a tank port 226, which is connected to a low-pressure reservoiror fluid return (not shown). The tank port 226 may be connected to thesame source of low-pressure fluid as the outlet port 118 of the MEMSmicrovalve 100 shown in FIG. 1.

A first load port 228 and a second load port 230 are formed in the bodyand communicate with the cavity 214. The first load port 228 and thesecond load port 230 are disposed on opposite sides of the supply port224. The first load port 228 and the second load port 230 are adapted tobe connected together to supply pressurized fluid to ahydraulically-operated component of the transmission or powertrain, asdescribed herein. Additional ports, channels, or troughs (not viewablein FIG. 2) may be formed on the upper surface of the cavity 214 oppositethe first load port 228 and the tank port 226. The additional troughshelp balance flow forces acting on the slider 212.

The slider 212 shown includes three openings therethrough. A firstopening 232, close to the piloted surface 216, is defined through theslider 212 to permit the fluid volume to equalize through the troughabove the tank port 226 with the pressure at the tank port 226,balancing forces acting vertically (into and out of the view shown inFIG. 2) on the slider 212. A second opening 234 through the slider 212forms an internal volume that is always in communication with the secondload port 230.

A web 236 between the second opening 234 and the first opening 232permits or prevents flow between the second load port 230 and the tankport 226 depending upon the position of the slider 212. In theillustrated position, the web 236 prevents flow between the second loadport 230 and the tank port 226. When the web 236 moves to the right (asviewed on the page in FIG. 2), a fluid pathway between the second loadport 230 and the tank port 226 is opened, venting any pressure presentat the second load port 230 to the low pressure reservoir connected tothe tank port 226.

A third opening 238 through the slider 212 permits the fluid volume inthe trough above the first load port 228 to equalize with the pressureat the first load port 228, balancing forces acting vertically (into andout of the view shown in FIG. 2) on the slider 212. A web 240 betweenthe second opening 234 and the third opening 238 prevents flow betweenthe supply port 224 and the second load port 230 in all positions of theslider 212.

A web 242 between the third opening 238 and the counter surface 222permits or prevents flow between the supply port 224 and the first loadport 228, depending upon the position of the slider 212. In theillustrated position, the web 242 prevents flow between the supply port224 and the first load port 228. When the slider 212 moves to the left(as viewed on the page in FIG. 2), a fluid pathway opens between thesupply port 224 and the first load port 228, supplying pressurized fluidto the load connected to the first load port 228.

The slider 212 cooperates with the walls of the cavity 214 to define thepiloted chamber 220 between the piloted surface 216 and the opposingwall of the cavity 214. A counter chamber 244 is defined between thecounter surface 222 and the opposing wall of the cavity 214. The counterchamber 244 is in fluid communication with the first load port 228 atall times. Additionally, two volumes 246 and 248 may be defined betweenrespective pairs of shoulders of the T-shaped plate forming the slider212 and the shoulders of the T-shaped cavity 214. The volumes 246 and248 are in communication with the tank port 226 at all times. In thismanner, a hydraulic lock of the slider 212 is prevented.

The total area of the piloted surface 216 of the slider 212 is largerthan the total area of the counter surface 222 of the slider 212.Therefore, when the pressures in the piloted chamber 220 and the counterchamber 244 are equal, the resultant unbalanced net force acting on theslider 212 will urge the slider 212 to the left (as viewed on the pagein FIG. 2).

Referring now to FIG. 3, the MEMS microvalve 100 and the MEMS-basedspool valve 200 may be implemented in a hybrid vehicle 300. Inparticular, the MEMS devices of FIGS. 1 and 2 may be implemented in apowertrain system 305 that may include an engine 310, two motors 315, atransmission 320, a clutch assembly 325, a valve body 330, a pump 335,and a control processor 340. The vehicle 300 may be a passenger orcommercial automobile. As such, the MEMS microvalve 100 and theMEMS-based spool valve 200 may be implemented in a hybrid electricvehicle, such as a plug-in hybrid electric vehicle (PHEV) or an extendedrange hybrid vehicle (EREV), or the like. Of course, the MEMS microvalve100 and the MEMS-based spool valve 200 may have other implementationsbesides use in the vehicle 300.

The engine 310 may include any device configured to provide a torque tothe transmission 320. For instance, the engine 310 may include aninternal combustion engine 310 configured to generate rotational motionby combusting a fossil fuel and air mixture. The rotational motiongenerated by the engine 310 may be output via a crankshaft 345. Further,the operation of the engine 310 may be controlled by an engine controlunit 350.

The motors 315 may each include any device configured to convertelectrical energy into motion. For instance, the motors 315 may receiveelectrical energy from a power source (not shown), such as a battery.Additionally, one or both of the motors 315 may further act as agenerator. That is, the motors 315 may be configured to convertrotational motion into electrical energy that may be stored by the powersource. The motors 315 may be configured to provide a torque to thetransmission 320. Like the engine 310, the motors 315 may output torqueto the transmission 320 via a crankshaft 345. The operation of themotors 315 may be controlled via one or more motor control units 355.Although two motors 315 are illustrated in FIG. 3, the vehicle 300 mayinclude any number of motors 315.

The transmission 320 may include any device configured to output atorque to wheels 360 of the vehicle 300. The transmission 320 mayinclude an input shaft 365, an output shaft 370, and a gearbox 375. Theinput shaft 365 may be used to receive the torque generated by theengine 310 and/or motors 315 either directly or through the clutchassembly 325 (discussed in greater detail below). Although notillustrated, additional clutch assemblies (not shown) may be disposedbetween the transmission and the motors 315. The output shaft 370 may beused to output a torque to wheels 360 of the vehicle 300. The gearbox375 may include gears of various sizes and configurations (e.g.,planetary) that may be used to change the rotational speed of the outputshaft 370 relative to the input shaft 365 and torque from the motors315. The gears in the gearbox 375 may be engaged and disengaged throughthe use of various clutches (not shown) within the gearbox 375. Indeed,one or more of the clutches in the gearbox 375 may be used instead of orin addition to the clutch assembly 325. The operation of thetransmission 320 may be controlled via a transmission control unit 380.In one possible approach, the transmission 320 may be configured toreceive torque from the engine 310, one or more of the motors 315, orall three simultaneously.

The clutch assembly 325 may be any hydraulically actuated device that isconfigured to transfer the torque generated by the engine 310 or themotors 315 to the transmission 320. For example, the clutch assembly 325may be operably connected to the crankshaft 345 of the engine 310 and/orthe motors 315 and the input shaft 365 of the transmission 320. Theclutch assembly 325 may include a driving mechanism (not shown) and adriven mechanism (not shown). The driving mechanism may be operablydisposed on the crankshaft 345. Accordingly, the driving mechanism mayrotate at the same speed as the crankshaft 345 of the engine 310 and/orthe motor 315. The driven mechanism may be operably disposed on theinput shaft 365, which may cause the driven mechanism and the inputshaft 365 to rotate at the same speeds. In one possible implementation,the clutch assembly 325 may be disposed within the gearbox 375 of thetransmission 320 or replaced by clutches disposed within the gearbox375.

The driving mechanism and the driven mechanism may be configured toengage one another. The engagement of the driving mechanism and thedriven mechanism may be controlled by the control processor 340, theengine control unit 350, the motor control unit 355, the transmissioncontrol unit 380, and/or any other device configured to generate acontrol signal. For instance, the transmission control unit 380 maygenerate one or more control signals to control the engagement of thedriving mechanism and driven mechanism based on factors such as a speedof the vehicle 300, a gear selection by the driver of the vehicle 300,etc. Further, the engagement of the driving mechanism and the drivenmechanism may be carried out hydraulically. That is, fluid pressure maycause the driving mechanism to engage the driven mechanism. Whenengaged, the driving mechanism and driven mechanism may rotate atsubstantially the same speeds. As such, the torque generated by theengine 310 is transferred to the transmission 320. Additionally, thedriving mechanism and the driven mechanism may be configured topartially engage, resulting in a slip across the driving and drivenmechanisms. This way, the driving mechanism may impart some of theengine torque to the driven mechanism.

The valve body 330 may be part of the transmission 320 and may include aplurality of valves (e.g., hydraulic devices), such as one or moreclutch control valves 382, a lube regulating valve 385, a line pressurecontrol valve 390, one or more synchronizer valves 395, and one or moreselectable one-way clutch control valves 397. Each of these and/or othervalves may be controlled by one or more MEMS devices, such as the MEMSmicrovalve 100 and/or the MEMS based spool valve 200 described above. Inone example approach, the MEMS microvalve 100 and/or the MEMS basedspool valve 200 may provide on/off control of one or more valves in thevalve body 330 or located elsewhere in the vehicle 300. As such, theMEMS microvalve 100 and/or the MEMS based spool valve 200 may replaceone or more on/off solenoids. The valve body 330 may further define afluid circuit that allows fluid to flow from the pump 335 to the variousportions of the transmission 320. The plurality of valves within thevalve body 330 may be used to control the flow of fluid from the pump335 and through the fluid circuit to the various components of thetransmission 320. One or more of the valves within the valve body 330may be electrically actuated (e.g., solenoid valves) or hydraulicallyactuated. In one example implementation, the valve body 330 may be partof the transmission 320 or a separate device. As such, one or more ofthe MEMS microvalve 100 and the MEMS based spool valve 200 may bedisposed within the valve body 330 or the transmission 320.

The clutch control valve 382 may include any device configured tocontrol the flow of fluid to, for instance, the clutch assembly 325. Thelube regulating valve 385 may include any device configured to controlthe flow of fluid to, for instance, a lubrication circuit. The linepressure control valve 390 may include any device configured to controlthe fluid pressure provided to the valve body 330 and/or any otherhydraulic device within the powertrain system 305. The synchronizervalve 395 may include any device configured to control fluid flow to asynchronizer. In one possible implementation, the synchronizer mayinclude a device that synchronizes a speed of rotation of two spinningobjects prior to engaging the objects. As such, the synchronizer may beused to synchronize the rotational speeds of a clutch prior toengagement of the clutch. The selectable one-way clutch control valve397 may include any device configured to control fluid flow to a one-wayclutch (e.g., a clutch that only transfers torque in a single rotationaldirection). Of course, the valve body 330 may include other valves thanthose described.

The pump 335 may include any device configured to provide pressurizedfluid to various components of the transmission 320, engine 310, and/orclutch assembly 325 via, for instance, the valve body 330. In oneparticular approach, the pump 335 may receive a commanded pressure from,for example, the control processor 340, the engine control unit 350, thetransmission control unit 380, or a combination of these or any othercomputing devices, and provide fluid at the commanded pressure. Thepowertrain system 305 may include any number of pumps 335 to providefluid to the various hydraulic devices in the powertrain system 305.

The control processor 340 may include any device configured to generatesignals that control the operation of one or more of the components inthe powertrain system 305. For instance, the control processor 340 maybe configured to control the operation of the pump 335 by generating asignal that represents the commanded pressure. Moreover, as described ingreater detail below, the control processor 340 may be configured tocontrol the operation of the MEMS devices. For instance, the controlprocessor 340 may be configured to generate signals that cause one ormore MEMS microvalves 100 within the powertrain system 305 to actuate.Additionally, the control processor 340 may be configured to generatesignals to actuate the various valves, such as solenoid valves, withinthe transmission 320. In one example implementation, one or more of theengine control unit 350, the motor control unit 355, and thetransmission control unit 380 may be configured to perform one or moreof the functions of the control processor 340. In this way, the enginecontrol unit 350, the motor control unit 355, and/or the transmissioncontrol unit 380 may control fluid flow from the pump 335 to variousdevices within the powertrain system 305. Further, the engine controlunit 350, the motor control unit 355, and/or the transmission controlunit 380 may be part of the control processor 340.

In general, computing systems and/or devices, such as the controlprocessor 340, the engine control unit 350, the motor control unit 355,and the transmission control unit 380, may employ any of a number ofcomputer operating systems and generally include computer-executableinstructions, where the instructions may be executable by one or morecomputing devices such as those listed above. Computer-executableinstructions may be compiled or interpreted from computer programscreated using a variety of well known programming languages and/ortechnologies, including, without limitation, and either alone or incombination, Java™, C, C++, Visual Basic, Java Script, Perl, etc. Ingeneral, a processor (e.g., a microprocessor) receives instructions,e.g., from a memory, a computer-readable medium, etc., and executesthese instructions, thereby performing one or more processes, includingone or more of the processes described herein. Such instructions andother data may be stored and transmitted using a variety of knowncomputer-readable media.

A computer-readable medium (also referred to as a processor-readablemedium) includes any non-transitory (e.g., tangible) medium thatparticipates in providing data (e.g., instructions) that may be read bya computer (e.g., by a processor of a compute). Such a medium may takemany forms, including, but not limited to, non-volatile media andvolatile media. Non-volatile media may include, for example, optical ormagnetic disks and other persistent memory. Volatile media may include,for example, dynamic random access memory (DRAM), which typicallyconstitutes a main memory. Such instructions may be transmitted by oneor more transmission 320 media, including coaxial cables, copper wireand fiber optics, including the wires that comprise a system bus coupledto a processor of a computer. Common forms of computer-readable mediainclude, for example, a floppy disk, a flexible disk, hard disk,magnetic tape, any other magnetic medium, a CD-ROM, DVD, any otheroptical medium, punch cards, paper tape, any other physical medium withpatterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any othermemory chip or cartridge, or any other medium from which a computer canread.

FIGS. 4-7 illustrate multiple schematic box diagrams of pressure controlsystems for hydraulic components within a transmission 320, such as thepowertrain shown in FIG. 3. Each of the plurality of options for thepressure control system shown and described may be used for operationand control of any of the plurality of components shown and described,including the clutch control valve 382, the lube regulating valve 385,the line pressure control valve 390, the synchronizer valve 395, and theselectable one-way clutch control valve 397. Furthermore, additionalpressure control system options may be created by combining the variousMEMS devices discussed with other MEMS devices and metal valves.

FIG. 4 shows a first option 400 for a pressure control system for ahydraulically-actuated component 410 within the powertrain. Thehydraulically-controlled component 410 may be any one of the componentsof the powertrain shown in FIG. 3. For example, and without limitation,the hydraulically-controlled component 410 may be one or more of: theclutch control valves 382, the lube regulating valve 385, the linepressure control valve 390, the synchronizer valves 395, and theselectable one-way clutch control valves 397. In some implementations ofthe powertrain, the hydraulically-controlled component 410 may actuallybe two or more of these components.

The first option 400 includes a pilot valve 412 controlling a regulatingvalve 414. The regulating valve 414 is in fluid communication with thepilot valve 412. The pilot valve 412 includes a first valve 416producing a pilot signal. The regulating valve 414 is configured toreceive the pilot signal and the regulating valve 414 is configured tooutput a control signal that controls the hydraulically-actuatedcomponent 410.

In the first option 400 shown in FIG. 4, the first valve 416 may includea MEMS device such as the MEMS microvalve 100 shown in FIG. 1. Theregulating valve 414 may further include a MEMS device such as theMEMS-based spool valve 200. Therefore, as described herein, the MEMSmicrovalve 100 may produce the pilot signal and communicates through thepilot port 120 to the piloted chamber 220 of the MEMS-based spool valve200.

Referring back to the example approaches illustrated in FIGS. 1 and 2,when the MEMS microvalve 100 shown in FIG. 1 is combined with theMEMS-based spool valve 200, either by attaching the two directlytogether or by fluidly connecting the pilot port 120 and piloted chamber220, the MEMS microvalve 100 acts on the MEMS-based spool valve 200 toalter the fluid flow and pressure to the first load port 228 and thesecond load port 230.

The inlet port 116 in the MEMS microvalve 100 is relatively small incomparison to the supply port 224 and the first load port 228 of theMEMS-based spool valve 200. In combined operation, the beam 112 of theMEMS microvalve 100 uncovers the inlet port 116, and fluid flows throughthe inlet port 116, the first chamber 122, and the outlet orifice 124 tothe outlet port 118. The inlet port 116 may act as an additional orificein this flow path.

Due to possible pressure drop through the inlet port 116, it may not bepossible to get the pressure in the piloted chamber 220 of theMEMS-based spool valve 200 up to the pressure provided by thehigh-pressure fluid source. The pressure in the counter chamber 244 mayachieve a higher pressure (at or near pump 335 outlet pressure) than maybe achieved in the piloted chamber 220, owing to the larger openings ofthe supply port 224 and the first load port 228 of the MEMS-based spoolvalve 200, and resultant low pressure drop when fluid flows throughthese ports. However, because the surface area of the piloted surface216 is greater than the surface area of the counter surface 222, theslider 212 can still be moved leftward (as viewed on the page in FIG. 2)even if the pressure in the piloted chamber 220 acting on the pilotedsurface 216 is less than the pressure in the counter chamber 244.

The MEMS-based spool valve 200 has three principal zones or positions ofoperation: a pressure increase position, a pressure hold position, and apressure decrease position. The MEMS-based spool valve 200 is shown inFIG. 2 in the pressure hold position, such that the MEMS-based spoolvalve 200 is holding pressurized fluid on the hydraulically-actuatedcomponent 410 (the load).

If the slider 212 is moved rightward (as viewed on the page in FIG. 2),the MEMS-based spool valve 200 is in the pressure decrease position.This may be accomplished when the control processor 340 or anothercomputing device commands the MEMS microvalve 100 to close by increasingelectric current supplied to the actuator 114. The first and second ribs132 and 134 of the actuator 114 expand, causing the beam 112 to pivotcounter-clockwise (bending the flexure pivot 126) and cover more of theinlet port 116. Flow decreases through the first chamber 122 from theinlet port 116 to the outlet port 118. The pressure drop across theoutlet orifice 124 decreases.

Pressure in the first chamber 122 and the pilot port 120 also decreases.Because the pilot port 120 is in direct fluid communication with thepiloted chamber 220, this results in an imbalance of the forces actingon the slider 212. The decreased force acting on the piloted surface 216(due to the lowered pressure in the piloted chamber 220) is now lessthan the unchanged force acting on the counter surface 222 due to thepressure in the counter chamber 244 (connected to the load).

The force imbalance urges the slider 212 of the MEMS-based spool valve200 to the right (as viewed in FIG. 2). The web 236 is thus movedrightward, permitting flow of pressurized fluid from thehydraulically-controlled component 410, through the second load port 230and through the second opening 234 in the slider 212. From there, someof the flow passes directly out of the tank port 226, while some flowmay pass up into the trough above the tank port 226, over the top of theweb 236, down through the first opening 232 and out the tank port 226.In this manner, pressure is released from the hydraulically-controlledcomponent 410 and vented to the low pressure reservoir connected to thetank port 226.

The slider 212 of the MEMS-based spool valve 200 will move back to thepressure hold position when the pressure in the counter chamber 244(acting through the first load port 228) is decreased sufficiently thatforces acting on the slider 212 urge the slider 212 to move to the left(as viewed in FIG. 2). With forces equalized, the slider 212 of theMEMS-based spool valve 200 will stop in the pressure hold position.Thus, the pressure at the load (as sensed through the first load port228 and the second load port 230) will be proportionate to theelectrical signal (current) supplied to the actuator 114.

To move the MEMS-based spool valve 200 into the pressure increaseposition, the control processor 340 or another computing device maydecrease current flow through the ribs of the actuator 114 and the beam112 of the MEMS microvalve 100 pivots clockwise to uncover more of theinlet port 116. This results in a pressure increase in the pilotedchamber 220, while the pressure in the counter chamber 244 remainsconstant. The slider 212 is moved leftward (as viewed in FIG. 2) due tothe resultant imbalance of forces acting on the slider 212. If theMEMS-based spool valve 200 was in the pressure decrease position, theleftward movement moves the slider valve back to the pressure holdposition shown in FIG. 2.

If the control processor 340 further decreases current flow and causesthe MEMS microvalve 100 to open further, the pressure in the pilotedchamber 220 further increases, urging the slider 212 of the MEMS-basedspool valve 200 further leftward (as viewed in FIG. 2) into the pressureincrease position. The web 242 is moved leftward, permitting flow ofpressurized fluid from the supply port 224 through the third opening 238in the slider 212. From the third opening 238, some of the flow passesdirectly out of the first load port 228, while some flow may pass upinto the trough over the top of the web 242, through the second counterchamber 244 and out of the first load port 228. In this manner, pressureis directed from the source of high-pressure fluid connected to thesupply port 224 and applied to the load connected to the first load port228 (e.g., the hydraulically-operated component 410).

The control signal produced by the MEMS-base spool valve 200 may havesufficient pressure and flow characteristics to control thehydraulically-controlled component 410. The pilot signal produced by theMEMS microvalve 100 may not be able to directly control thehydraulically-controlled component 410.

Referring back to FIG. 4, the first option 400 may further include aMEMS pressure sensor 420 that may be configured to sense the pressureprofile of the control signal from the regulating valve 414. The controlprocessor 340 or another computing device may be configured to receiveinput from the MEMS pressure sensor 420 and to provide output to theMEMS microvalve 100 in the pilot valve 412 to regulate the systempressure in response to input from the MEMS pressure sensor 420.Therefore, with the MEMS pressure sensor 420 and the control processor340 or another computing device, the first option 400 may be configuredfor closed-loop feedback and adjustment of the control signal sent tothe hydraulically-controlled component 410.

The hydraulically-controlled component 410 may be any one of thecomponents of the powertrain shown in FIG. 3. For example, and withoutlimitation, the hydraulically-controlled component 410 may be one ormore of: the clutch control valves 382, the lube regulating valve 385,the line pressure control valve 390, the synchronizer valves 395, andthe selectable one-way clutch control valves 397. In someimplementations of the powertrain, the hydraulically-controlledcomponent 410 may actually be two or more of these components.

FIG. 5 shows a second option 500 for a pressure control system for thehydraulically-actuated component 510 within the powertrain. The secondoption 500 includes a pilot valve 512 controlling a regulating valve514. The regulating valve 514 is in fluid communication with the pilotvalve 512.

The pilot valve 512 may include a first valve 516 producing a pilotsignal. However, unlike the first option 400 shown in FIG. 4, in thesecond option 500, the pilot valve 512 also includes a second valve 518,which steps up, or amplifies, the pilot signal to an amplified pilotsignal. The regulating valve 514 is configured to receive the amplifiedpilot signal and the regulating valve 514 is configured to output acontrol signal, which controls the hydraulically-actuated component 510.The hydraulically-controlled component 510 may be any one of thecomponents of the powertrain shown in FIG. 3. For example, and withoutlimitation, the hydraulically-controlled component 510 may be one of:the clutch control valves 382, the lube regulating valve 385, the linepressure control valve 390, the synchronizer valves 395, and theselectable one-way clutch control valves 397. In some embodiments of thepowertrain, the hydraulically-controlled component 510 may actually betwo or more of these components.

In the second option 500 shown in FIG. 5, the first valve 516 mayinclude the MEMS microvalve 100 shown in FIG. 1 and the second valve 518is the MEMS-based spool valve 200. Therefore, as already describedherein, the MEMS microvalve 100 selectively produces the pilot signaland communicates through the pilot port 120 to the piloted chamber 220of the MEMS-based spool valve 200. However, with the second option 500,the output of the MEMS-based spool valve 200 is the amplified pilotsignal, which is then used by the regulating valve 514.

In the second option 500 shown in FIG. 5, the regulating valve 514 mayinclude a conventional mechanical regulating valve. Generally, theconventional mechanical regulating valve is a regulating valve producedby mechanical machining processes. Based upon the amplified pilot signalprovided by the pilot valve 512, the conventional mechanical regulatingvalve provides the control signal for the hydraulically actuatedcomponent 510.

The amplified pilot signal produced by the pilot valve 512 (includingboth the first valve 516 and the second valve 518 (the MEMS-base spoolvalve 200)) has sufficient pressure and flow characteristics to controlthe conventional mechanical regulating valve, which may then control thehydraulically-controlled component 510. However, the pilot signalproduced by the first valve 516 (the MEMS microvalve 100) of the pilotvalve 512 may not be able to directly pilot the conventional mechanicalregulating valve or to directly control the hydraulically-controlledcomponent 510. The conventional mechanical regulating valve furtherincreases the pressure and flow characteristics used to control thehydraulically-controlled component 510, as compared to the first option400 shown in FIG. 4.

The second option 500 may further include one or more MEMS-basedpressure sensors such as a MEMS pressure sensor 520. However, when used,the MEMS pressure sensors 520 are configured to sense the pressureprofile of amplified pilot signal from the pilot valve 512 or of thecontrol signal from the regulating valve 514. In some implementations,only one of the MEMS pressure sensors 520 may be used. If used to sensethe pressure profile of the pilot signal, the MEMS pressure sensor 520may be packaged into a single package along with the MEMS microvalve 100and the MEMS-based spool valve 200 for the pilot valve 512.

The control processor 340 or another computing device is configured toreceive input from one of the MEMS pressure sensors 520 and to provideoutput to the MEMS microvalve 100 in the pilot valve 512 to regulate thesystem pressure in response to input from one of the MEMS pressuresensors 520. Therefore, the MEMS pressure sensors 520 provideclosed-loop feedback and adjustment of the control signal sent to thehydraulically-controlled component 510.

The hydraulically-controlled component 510 may be any one of thecomponents of the powertrain shown in FIG. 3. For example, and withoutlimitation, the hydraulically-controlled component 510 may be one of:the clutch control valves 382, the lube regulating valve 385, the linepressure control valve 390, the synchronizer valves 395, and theselectable one-way clutch control valves 397. In some embodiments of thepowertrain, the hydraulically-controlled component 510 may actually betwo or more of these components. Each of the first option 400 and thesecond option 500 may be used with any of the components of thepowertrain.

FIG. 6 shows a third option 600 for a pressure control system for thehydraulically-actuated component 610 within the powertrain. The thirdoption 600 includes a pilot valve 612 controlling a regulating valve614. The regulating valve 614 is in fluid communication with the pilotvalve 612.

The pilot valve 612 includes a first valve 616 producing a pilot signal.The regulating valve 614 is configured to receive the pilot signal andthe regulating valve 614 is configured to output a control signal, whichcontrols the hydraulically-actuated component 610. Thehydraulically-controlled component 610 may be any one of the componentsof the powertrain shown in FIG. 3. For example, and without limitation,the hydraulically-controlled component 610 may be one of: the clutchcontrol valves 382, the lube regulating valve 385, the line pressurecontrol valve 390, the synchronizer valves 395, and the selectableone-way clutch control valves 397. In some embodiments of the powertrain305, the hydraulically-controlled component 610 may actually be two ormore of these components. Each of the first option 400, the secondoption 500, and the third option 600 may be used with any of thecomponents of the powertrain.

In the third option 600 shown in FIG. 6, the first valve 616 may includethe MEMS microvalve 100 shown in FIG. 1, but there is no second valveforming the pilot valve similar to 512. Therefore, unlike the firstoption 400 shown in FIG. 4 and in the second option 500 shown in FIG. 5,the MEMS microvalve 100 communicates the pilot signal directly to theregulating valve 614, which may include a small mechanical spool valve.

Generally, the small mechanical spool valve is a regulating valveproduced by mechanical machining processes, but on a smaller scale thanthe conventional mechanical regulating valve. Based upon the(un-amplified) pilot signal provided by the pilot valve 612, the smallmechanical spool valve provides the control signal for thehydraulic-actuated component 610. Compared to the conventionalmechanical regulating valve used in the second option 500 shown in FIG.5, the small mechanical spool valve is, for example, on the order halfof the size of the conventional mechanical regulating valve.

The pilot signal produced by the pilot valve 612 (including only theMEMS microvalve 100) may have sufficient pressure and flowcharacteristics to control the small mechanical spool valve used for theregulating valve 614, but may not be capable of directly controlling theconventional mechanical regulating valve used in the second option 500.The small mechanical spool valve may then control thehydraulically-controlled component 610. Depending on the response timeand flow and pressure requirements, however, the pilot valve 612 may beused to control the conventional mechanical regulating valve describedabove.

The third option 600 may further include one or more optional MEMSpressure sensors 620. However, when used, the MEMS pressure sensors 620are configured to sense the pressure profile of pilot signal from thepilot valve 612 or of the control signal from the regulating valve 614.In most configurations, only one of the MEMS pressure sensors 620 willbe used. If used to sense the pressure profile of the pilot signal, theMEMS pressure sensor 620 may be packaged into a single package alongwith the MEMS microvalve 100 for the pilot valve 612.

The control processor 340 or other computing device, such as the enginecontrol unit 350, is configured to receive input from one of the MEMSpressure sensors 620 and to provide output to the MEMS microvalve 100 inthe pilot valve 612 to regulate the system pressure in response to inputfrom one of the MEMS pressure sensors 620. Therefore, the MEMS pressuresensors 620 provide closed-loop feedback and adjustment of the controlsignal sent to the hydraulically-controlled component 610.

The hydraulically-controlled component 610 may be any one of thecomponents of the powertrain shown in FIG. 3. For example, and withoutlimitation, the hydraulically-controlled component 610 may be one of:the clutch control valves 382, the lube regulating valve 385, the linepressure control valve 390, the synchronizer valves 395, and theselectable one-way clutch control valves 397. In some embodiments of thepowertrain 305, the hydraulically-controlled component 610 may actuallybe two or more of these components. Each of the first option 400, thesecond option 500, and the third option 600 may be used with any of thecomponents of the powertrain.

FIG. 7 shows a fourth option 700 for a pressure control system for thehydraulically-actuated component 710 within the powertrain. The fourthoption 700 includes a pilot valve 712 controlling a regulating valve714. The regulating valve 714 is in fluid communication with the pilotvalve 712. The hydraulically-controlled component 710 may be any one ofthe components of the powertrain shown in FIG. 3. For example, andwithout limitation, the hydraulically-controlled component 710 may beone or more of: the clutch control valves 382, the lube regulating valve385, the line pressure control valve 390, the synchronizer valves 395,and the selectable one-way clutch control valves 397. In someembodiments of the powertrain, the hydraulically-controlled component710 may actually be two or more of these components.

The pilot valve 712 includes a first valve 716 producing a pilot signal.Similar to the second option 500 shown in FIG. 5, the pilot valve 712also includes a second valve 718, which steps up, or amplifies, thepilot signal to an amplified pilot signal. The regulating valve 714 isagain configured to receive the amplified pilot signal and theregulating valve 714 is configured to output a control signal, whichcontrols the hydraulically-actuated component 710.

In the fourth option 700 shown in FIG. 7, the first valve 716 mayinclude the MEMS microvalve 100 shown in FIG. 1. However, the secondvalve 718 may include the small mechanical spool valve. In the fourthoption 700 shown in FIG. 7, the regulating valve 714 is again aconventional mechanical regulating valve. Based upon the amplified pilotsignal provided by the pilot valve 712, the conventional mechanicalregulating valve provides the control signal for the hydraulic-actuatedcomponent 710.

Therefore, as already described herein, the MEMS microvalve 100selectively produces the pilot signal and communicates through the pilotport 120 to the piloted chamber 220 of the MEMS-based spool valve 200.However, with the fourth option 700, the output of the small mechanicalspool valve is the amplified pilot signal, which is then used by theregulating valve 714. In the fourth option 700, the small mechanicalspool valve functions similarly to the MEMS-based spool valve 200 usedas the second valve 518 in the second option 500 shown in FIG. 5.However, the small mechanical spool valve used as the second valve 718for the fourth option 700 may be at least 100 times larger than theMEMS-based spool valve 200 used for the second valve 518 in the secondoption 500.

The amplified pilot signal produced by the pilot valve 712 (includingboth the first valve 716 and the second valve 718) may have sufficientpressure and flow characteristics to control the conventional mechanicalregulating valve, which may then control the hydraulically-controlledcomponent 710. However, the pilot signal produced by the first valve 716alone (the MEMS microvalve 100) may not be able to directly pilot theconventional mechanical regulating valve or to directly control thehydraulically-controlled component 710. The conventional mechanicalregulating valve further increases the pressure and flow characteristicsused to control the hydraulically-controlled component 710. Depending onthe response time and flow and pressure requirements, however, the pilotvalve 712 may be used to control the conventional mechanical regulatingvalve described above.

The fourth option 700 may further include one or more optional MEMSpressure sensors 720. However, when used, the MEMS pressure sensors 720are configured to sense the pressure profile of pilot signal from thepilot valve 712 or of the control signal from the regulating valve 714.In most configurations, only one of the MEMS pressure sensors 720 willbe used.

The control processor 340 or other computing device, such as the enginecontrol unit 350, is configured to receive input from one of the MEMSpressure sensors 720 and to provide output to the MEMS microvalve 100 inthe pilot valve 712 to regulate the system pressure in response to inputfrom one of the MEMS pressure sensors 720. Therefore, the MEMS pressuresensors 720 provide closed-loop feedback and adjustment of the controlsignal sent to the hydraulically-controlled component 710.

The hydraulically-controlled component 710 may be any one of thecomponents of the powertrain shown in FIG. 3. For example, and withoutlimitation, the hydraulically-controlled component 710 may be one ormore of: the clutch control valves 382, the lube regulating valve 385,the line pressure control valve 390, the synchronizer valves 395, andthe selectable one-way clutch control valves 397. In some embodiments ofthe powertrain, the hydraulically-controlled component 710 may actuallybe two or more of these components. Each of the first option 400, thesecond option 500, the third option 600, and the fourth option 700 maybe used with any of the components of the powertrain.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

The invention claimed is:
 1. A powertrain system in a hybrid vehiclecomprising: a transmission configured to receive a torque from at leastone of an engine and at least one motor; the transmission having ahydraulic device; a micro-electro-mechanical system (MEMS) pilotmicrovalve configured to output an unamplified pilot signal through amicroslider valve to a mechanical regulating valve; wherein themechanical regulating valve is operably connected to the MEMS pilotmicrovalve and the hydraulic device; wherein the mechanical regulatingvalve is configured to receive the unamplified pilot signal from theMEMS pilot microvalve and to output a control signal; and wherein fluidis directed to the hydraulic device in response to the control signal.2. A powertrain system in a hybrid vehicle comprising: a transmissionconfigured to receive a torque from at least one of an engine and atleast one motor: the transmission having a hydraulic device: amicro-electro-mechanical system (MEMS) pilot microvalve configured tooutput an unamplified pilot signal through a microslider valve to amechanical regulating valve: wherein the mechanical regulating valveincludes a spool valve; wherein the mechanical regulating valve isoperably connected to the MEMS pilot microvalve and the hydraulicdevice; wherein the mechanical regulating valve is configured to receivethe unamplified pilot signal from the MEMS pilot microvalve and tooutput a control signal; and wherein fluid is directed to the hydraulicdevice in response to the control signal.
 3. A powertrain system as setforth in claim 1, wherein the hydraulic device includes at least one ofa clutch assembly, a lube regulating valve, a line control pressurevalve, a synchronizer valve, and a selectable one-way clutch controlvalve.
 4. A powertrain system as set forth in claim 1, furthercomprising a pressure sensor operably disposed between the pilot valveand the hydraulic device.
 5. A powertrain system as set forth in claim4, wherein the pressure sensor includes a MEMS-based pressure sensor. 6.A vehicle comprising: an engine configured to generate a torque; atleast one motor configured to generate a torque; a transmissionconfigured to receive torque from at least one of the engine and the atleast one motor; and a clutch assembly configured to transfer a torquefrom the engine to the transmission; wherein the transmission includes ahydraulic device operably connected to a micro-electro-mechanicalsystems (MEMS) pilot microvalve and a mechanical regulating valve;wherein the MEMS pilot microvalve is configured to output an unamplifiedpilot signal through a microslider valve to the mechanical regulatingvalve; wherein the mechanical regulating valve is configured to receivethe unamplified pilot signal from the MEMS pilot microvalve and tooutput a control signal; and wherein fluid is directed to the hydraulicdevice in response to the control signal.
 7. A vehicle as set forth inclaim 6, wherein the regulator valve includes a spool valve.
 8. Avehicle as set forth in claim 6, wherein the hydraulic device includesat least one of a clutch assembly, a lube regulating valve, a linecontrol pressure valve, a synchronizer valve, and a selectable one-wayclutch control valve.
 9. A vehicle as set forth in claim 6, furthercomprising a MEMS-based pressure sensor operably disposed between thepilot valve and the hydraulic device.